/*
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU General Public License along with
 * this program. If not, see <http://www.gnu.org/licenses/>.
 */
package net.sf.l2j.gameserver;

import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Logger;

import net.sf.l2j.Config;
import net.sf.l2j.gameserver.network.L2GameClient;
import net.sf.l2j.mmocore.ReceivablePacket;
import net.sf.l2j.util.StringUtil;

/**
 * <p>
 * This class is made to handle all the ThreadPools used in L2j.
 * </p>
 * <p>
 * Scheduled Tasks can either be sent to a {@link #_generalScheduledThreadPool "general"} or {@link #_effectsScheduledThreadPool "effects"} {@link ScheduledThreadPoolExecutor ScheduledThreadPool}: The "effects" one is used for every effects (skills, hp/mp regen ...) while the "general" one is used
 * for everything else that needs to be scheduled.<br>
 * There also is an {@link #_aiScheduledThreadPool "ai"} {@link ScheduledThreadPoolExecutor ScheduledThreadPool} used for AI Tasks.
 * </p>
 * <p>
 * Tasks can be sent to {@link ScheduledThreadPoolExecutor ScheduledThreadPool} either with:
 * <ul>
 * <li>{@link #scheduleEffect(Runnable, long)} : for effects Tasks that needs to be executed only once.</li>
 * <li>{@link #scheduleGeneral(Runnable, long)} : for scheduled Tasks that needs to be executed once.</li>
 * <li>{@link #scheduleAi(Runnable, long)} : for AI Tasks that needs to be executed once</li>
 * </ul>
 * or
 * <ul>
 * <li>{@link #scheduleEffectAtFixedRate(Runnable, long, long)} : for effects Tasks that needs to be executed periodically.</li>
 * <li>{@link #scheduleGeneralAtFixedRate(Runnable, long, long)} : for scheduled Tasks that needs to be executed periodically.</li>
 * <li>{@link #scheduleAiAtFixedRate(Runnable, long, long)} : for AI Tasks that needs to be executed periodically</li>
 * </ul>
 * </p>
 * <p>
 * For all Tasks that should be executed with no delay asynchronously in a ThreadPool there also are usual {@link ThreadPoolExecutor ThreadPools} that can grow/shrink according to their load.:
 * <ul>
 * <li>{@link #_generalPacketsThreadPool GeneralPackets} where most packets handler are executed.</li>
 * <li>{@link #_ioPacketsThreadPool I/O Packets} where all the i/o packets are executed.</li>
 * <li>There will be an AI ThreadPool where AI events should be executed</li>
 * <li>A general ThreadPool where everything else that needs to run asynchronously with no delay should be executed ({@link net.sf.l2j.gameserver.model.actor.knownlist KnownList} updates, SQL updates/inserts...)?</li>
 * </ul>
 * </p>
 * @author -Wooden-
 */
@SuppressWarnings("rawtypes")
public class ThreadPoolManager
{
	protected static final Logger _log = Logger.getLogger(ThreadPoolManager.class.getName());

	private final ScheduledThreadPoolExecutor _effectsScheduledThreadPool;
	private final ScheduledThreadPoolExecutor _generalScheduledThreadPool;

	private final ThreadPoolExecutor _generalPacketsThreadPool;
	private final ThreadPoolExecutor _ioPacketsThreadPool;

	// will be really used in the next AI implementation.
	private final ThreadPoolExecutor _aiThreadPool;

	private final ThreadPoolExecutor _generalThreadPool;

	// temp
	private final ScheduledThreadPoolExecutor _aiScheduledThreadPool;

	/** temp workaround for VM issue */
	private static final long MAX_DELAY = Long.MAX_VALUE / 1000000 / 2;

	private boolean _shutdown;

	public static ThreadPoolManager getInstance()
	{
		return SingletonHolder._instance;
	}

	private ThreadPoolManager()
	{
		_effectsScheduledThreadPool = new ScheduledThreadPoolExecutor(Config.THREAD_P_EFFECTS, new PriorityThreadFactory("EffectsSTPool", Thread.NORM_PRIORITY));
		_generalScheduledThreadPool = new ScheduledThreadPoolExecutor(Config.THREAD_P_GENERAL, new PriorityThreadFactory("GerenalSTPool", Thread.NORM_PRIORITY));

		_ioPacketsThreadPool = new ThreadPoolExecutor(Config.IO_PACKET_THREAD_CORE_SIZE, Integer.MAX_VALUE, 5L, TimeUnit.SECONDS, new LinkedBlockingQueue<>(), new PriorityThreadFactory("I/O Packet Pool", Thread.NORM_PRIORITY + 1));

		_generalPacketsThreadPool = new ThreadPoolExecutor(Config.GENERAL_PACKET_THREAD_CORE_SIZE, Config.GENERAL_PACKET_THREAD_CORE_SIZE + 2, 15L, TimeUnit.SECONDS, new LinkedBlockingQueue<>(), new PriorityThreadFactory("Normal Packet Pool", Thread.NORM_PRIORITY + 1));

		_generalThreadPool = new ThreadPoolExecutor(Config.GENERAL_THREAD_CORE_SIZE, Config.GENERAL_THREAD_CORE_SIZE + 2, 5L, TimeUnit.SECONDS, new LinkedBlockingQueue<>(), new PriorityThreadFactory("General Pool", Thread.NORM_PRIORITY));

		// will be really used in the next AI implementation.
		_aiThreadPool = new ThreadPoolExecutor(1, Config.AI_MAX_THREAD, 10L, TimeUnit.SECONDS, new LinkedBlockingQueue<>());

		_aiScheduledThreadPool = new ScheduledThreadPoolExecutor(Config.AI_MAX_THREAD, new PriorityThreadFactory("AISTPool", Thread.NORM_PRIORITY));
	}

	public static long validateDelay(long delay)
	{
		if (delay < 0)
		{
			delay = 0;
		}
		else if (delay > MAX_DELAY)
		{
			delay = MAX_DELAY;
		}
		return delay;
	}

	public ScheduledFuture scheduleEffect(Runnable r, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			return _effectsScheduledThreadPool.schedule(r, delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			/* shutdown, ignore */
			return null;
		}
	}

	public ScheduledFuture scheduleEffectAtFixedRate(Runnable r, long initial, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			initial = ThreadPoolManager.validateDelay(initial);
			return _effectsScheduledThreadPool.scheduleAtFixedRate(r, initial, delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			/* shutdown, ignore */
			return null;
		}
	}

	public boolean removeEffect(Runnable r)
	{
		return _effectsScheduledThreadPool.remove(r);
	}

	public ScheduledFuture scheduleGeneral(Runnable r, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			return _generalScheduledThreadPool.schedule(r, delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			/* shutdown, ignore */
			return null;
		}
	}

	public ScheduledFuture scheduleGeneralAtFixedRate(Runnable r, long initial, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			initial = ThreadPoolManager.validateDelay(initial);
			return _generalScheduledThreadPool.scheduleAtFixedRate(r, initial, delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			/* shutdown, ignore */
			return null;
		}
	}

	public boolean removeGeneral(Runnable r)
	{
		return _generalScheduledThreadPool.remove(r);
	}

	public ScheduledFuture scheduleAi(Runnable r, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			return _aiScheduledThreadPool.schedule(r, delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			/* shutdown, ignore */
			return null;
		}
	}

	public ScheduledFuture scheduleAiAtFixedRate(Runnable r, long initial, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			initial = ThreadPoolManager.validateDelay(initial);
			return _aiScheduledThreadPool.scheduleAtFixedRate(r, initial, delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			/* shutdown, ignore */
			return null;
		}
	}

	public void executePacket(ReceivablePacket<L2GameClient> pkt)
	{
		_generalPacketsThreadPool.execute(pkt);
	}

	public void executeCommunityPacket(Runnable r)
	{
		_generalPacketsThreadPool.execute(r);
	}

	public void executeIOPacket(ReceivablePacket<L2GameClient> pkt)
	{
		_ioPacketsThreadPool.execute(pkt);
	}

	public void executeTask(Runnable r)
	{
		_generalThreadPool.execute(r);
	}

	public void executeAi(Runnable r)
	{
		_aiThreadPool.execute(r);
	}

	public String[] getStats()
	{
		return new String[]
		{
			"STP:",
			" + Effects:",
			" |- ActiveThreads:   " + _effectsScheduledThreadPool.getActiveCount(),
			" |- getCorePoolSize: " + _effectsScheduledThreadPool.getCorePoolSize(),
			" |- PoolSize:        " + _effectsScheduledThreadPool.getPoolSize(),
			" |- MaximumPoolSize: " + _effectsScheduledThreadPool.getMaximumPoolSize(),
			" |- CompletedTasks:  " + _effectsScheduledThreadPool.getCompletedTaskCount(),
			" |- ScheduledTasks:  " + (_effectsScheduledThreadPool.getTaskCount() - _effectsScheduledThreadPool.getCompletedTaskCount()),
			" | -------",
			" + General:",
			" |- ActiveThreads:   " + _generalScheduledThreadPool.getActiveCount(),
			" |- getCorePoolSize: " + _generalScheduledThreadPool.getCorePoolSize(),
			" |- PoolSize:        " + _generalScheduledThreadPool.getPoolSize(),
			" |- MaximumPoolSize: " + _generalScheduledThreadPool.getMaximumPoolSize(),
			" |- CompletedTasks:  " + _generalScheduledThreadPool.getCompletedTaskCount(),
			" |- ScheduledTasks:  " + (_generalScheduledThreadPool.getTaskCount() - _generalScheduledThreadPool.getCompletedTaskCount()),
			" | -------",
			" + AI:",
			" |- ActiveThreads:   " + _aiScheduledThreadPool.getActiveCount(),
			" |- getCorePoolSize: " + _aiScheduledThreadPool.getCorePoolSize(),
			" |- PoolSize:        " + _aiScheduledThreadPool.getPoolSize(),
			" |- MaximumPoolSize: " + _aiScheduledThreadPool.getMaximumPoolSize(),
			" |- CompletedTasks:  " + _aiScheduledThreadPool.getCompletedTaskCount(),
			" |- ScheduledTasks:  " + (_aiScheduledThreadPool.getTaskCount() - _aiScheduledThreadPool.getCompletedTaskCount()),
			"TP:",
			" + Packets:",
			" |- ActiveThreads:   " + _generalPacketsThreadPool.getActiveCount(),
			" |- getCorePoolSize: " + _generalPacketsThreadPool.getCorePoolSize(),
			" |- MaximumPoolSize: " + _generalPacketsThreadPool.getMaximumPoolSize(),
			" |- LargestPoolSize: " + _generalPacketsThreadPool.getLargestPoolSize(),
			" |- PoolSize:        " + _generalPacketsThreadPool.getPoolSize(),
			" |- CompletedTasks:  " + _generalPacketsThreadPool.getCompletedTaskCount(),
			" |- QueuedTasks:     " + _generalPacketsThreadPool.getQueue().size(),
			" | -------",
			" + I/O Packets:",
			" |- ActiveThreads:   " + _ioPacketsThreadPool.getActiveCount(),
			" |- getCorePoolSize: " + _ioPacketsThreadPool.getCorePoolSize(),
			" |- MaximumPoolSize: " + _ioPacketsThreadPool.getMaximumPoolSize(),
			" |- LargestPoolSize: " + _ioPacketsThreadPool.getLargestPoolSize(),
			" |- PoolSize:        " + _ioPacketsThreadPool.getPoolSize(),
			" |- CompletedTasks:  " + _ioPacketsThreadPool.getCompletedTaskCount(),
			" |- QueuedTasks:     " + _ioPacketsThreadPool.getQueue().size(),
			" | -------",
			" + General Tasks:",
			" |- ActiveThreads:   " + _generalThreadPool.getActiveCount(),
			" |- getCorePoolSize: " + _generalThreadPool.getCorePoolSize(),
			" |- MaximumPoolSize: " + _generalThreadPool.getMaximumPoolSize(),
			" |- LargestPoolSize: " + _generalThreadPool.getLargestPoolSize(),
			" |- PoolSize:        " + _generalThreadPool.getPoolSize(),
			" |- CompletedTasks:  " + _generalThreadPool.getCompletedTaskCount(),
			" |- QueuedTasks:     " + _generalThreadPool.getQueue().size(),
			" | -------",
			" + AI:",
			" |- Not Done"
		};
	}

	private class PriorityThreadFactory implements ThreadFactory
	{
		private final int _prio;
		private final String _name;
		private final AtomicInteger _threadNumber = new AtomicInteger(1);
		private final ThreadGroup _group;

		public PriorityThreadFactory(String name, int prio)
		{
			_prio = prio;
			_name = name;
			_group = new ThreadGroup(_name);
		}

		/*
		 * (non-Javadoc)
		 * @see java.util.concurrent.ThreadFactory#newThread(java.lang.Runnable)
		 */
		@Override
		public Thread newThread(Runnable r)
		{
			Thread t = new Thread(_group, r);
			t.setName(_name + "-" + _threadNumber.getAndIncrement());
			t.setPriority(_prio);
			return t;
		}

		public ThreadGroup getGroup()
		{
			return _group;
		}
	}

	/**
	 *
	 */
	public void shutdown()
	{
		_shutdown = true;
		try
		{
			_effectsScheduledThreadPool.awaitTermination(1, TimeUnit.SECONDS);
			_generalScheduledThreadPool.awaitTermination(1, TimeUnit.SECONDS);
			_generalPacketsThreadPool.awaitTermination(1, TimeUnit.SECONDS);
			_ioPacketsThreadPool.awaitTermination(1, TimeUnit.SECONDS);
			_generalThreadPool.awaitTermination(1, TimeUnit.SECONDS);
			_aiThreadPool.awaitTermination(1, TimeUnit.SECONDS);
			_effectsScheduledThreadPool.shutdown();
			_generalScheduledThreadPool.shutdown();
			_generalPacketsThreadPool.shutdown();
			_ioPacketsThreadPool.shutdown();
			_generalThreadPool.shutdown();
			_aiThreadPool.shutdown();
			_log.info("All ThreadPools are now stopped.");
		}
		catch (InterruptedException e)
		{
			e.printStackTrace();
		}
	}

	public boolean isShutdown()
	{
		return _shutdown;
	}

	/**
	 *
	 */
	public void purge()
	{
		_effectsScheduledThreadPool.purge();
		_generalScheduledThreadPool.purge();
		_aiScheduledThreadPool.purge();
		_ioPacketsThreadPool.purge();
		_generalPacketsThreadPool.purge();
		_generalThreadPool.purge();
		_aiThreadPool.purge();
	}

	/**
	 * @return 
	 *
	 */
	public String getPacketStats()
	{
		StringBuilder sb = new StringBuilder(1000);
		ThreadFactory tf = _generalPacketsThreadPool.getThreadFactory();
		if (tf instanceof PriorityThreadFactory)
		{
			StringUtil.append(sb, "General Packet Thread Pool:\r\n");
			StringUtil.append(sb, "Tasks in the queue: " + _generalPacketsThreadPool.getQueue().size() + "\r\n");
			StringUtil.append(sb, "Showing threads stack trace:\r\n");
			PriorityThreadFactory ptf = (PriorityThreadFactory) tf;
			int count = ptf.getGroup().activeCount();
			Thread[] threads = new Thread[count + 2];
			ptf.getGroup().enumerate(threads);
			StringUtil.append(sb, "There should be " + count + " Threads\r\n");
			for (Thread t : threads)
			{
				if (t == null)
				{
					continue;
				}
				StringUtil.append(sb, t.getName() + "\r\n");
				for (StackTraceElement ste : t.getStackTrace())
				{
					StringUtil.append(sb, ste.toString());
					StringUtil.append(sb, "\r\n");
				}
			}
		}
		StringUtil.append(sb, "Packet Tp stack traces printed.\r\n");
		return sb.toString();
	}

	public String getIOPacketStats()
	{
		StringBuilder sb = new StringBuilder(1000);
		ThreadFactory tf = _ioPacketsThreadPool.getThreadFactory();
		if (tf instanceof PriorityThreadFactory)
		{
			StringUtil.append(sb, "I/O Packet Thread Pool:\r\n");
			StringUtil.append(sb, "Tasks in the queue: " + _ioPacketsThreadPool.getQueue().size() + "\r\n");
			StringUtil.append(sb, "Showing threads stack trace:\r\n");
			PriorityThreadFactory ptf = (PriorityThreadFactory) tf;
			int count = ptf.getGroup().activeCount();
			Thread[] threads = new Thread[count + 2];
			ptf.getGroup().enumerate(threads);
			StringUtil.append(sb, "There should be " + count + " Threads\r\n");
			for (Thread t : threads)
			{
				if (t == null)
				{
					continue;
				}
				StringUtil.append(sb, t.getName() + "\r\n");
				for (StackTraceElement ste : t.getStackTrace())
				{
					StringUtil.append(sb, ste.toString());
					StringUtil.append(sb, "\r\n");
				}
			}
		}
		StringUtil.append(sb, "Packet Tp stack traces printed.\r\n");
		return sb.toString();
	}

	public String getGeneralStats()
	{
		StringBuilder sb = new StringBuilder(1000);
		ThreadFactory tf = _generalThreadPool.getThreadFactory();
		if (tf instanceof PriorityThreadFactory)
		{
			StringUtil.append(sb, "General Thread Pool:\r\n");
			StringUtil.append(sb, "Tasks in the queue: " + _generalThreadPool.getQueue().size() + "\r\n");
			StringUtil.append(sb, "Showing threads stack trace:\r\n");
			PriorityThreadFactory ptf = (PriorityThreadFactory) tf;
			int count = ptf.getGroup().activeCount();
			Thread[] threads = new Thread[count + 2];
			ptf.getGroup().enumerate(threads);
			StringUtil.append(sb, "There should be " + count + " Threads\r\n");
			for (Thread t : threads)
			{
				if (t == null)
				{
					continue;
				}
				StringUtil.append(sb, t.getName() + "\r\n");
				for (StackTraceElement ste : t.getStackTrace())
				{
					StringUtil.append(sb, ste.toString());
					StringUtil.append(sb, "\r\n");
				}
			}
		}
		StringUtil.append(sb, "Packet Tp stack traces printed.\r\n");
		return sb.toString();
	}
	
	private static class SingletonHolder
	{
		private static final ThreadPoolManager _instance = new ThreadPoolManager();
	}
}